Re: COPY Transform support

Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
> Tom Lane wrote:
>> (One of the issues that'd have to be addressed to allow a table source
>> syntax is whether it's sane to allow multiple COPY FROM STDIN in a
>> single query. If so, how does it work; if not, how do we prevent it?)

> I don't see why it shouldn't work. I see that copy.c now looks like it's
> reentrant, unlike the bad days of old. Could we make each COPY target
> behave like an SRF, stashing its data in a tuplestore?

The first question is what is the wire-protocol definition. In
particular, how would the client know what order to send the COPY
datasets in, if a single query might include multiple COPY FROM STDIN
segments?

Another point is that we surely don't want the implementation to force
use of a tuplestore all the time, so I'm not sure I buy that we can
prevent interleaving of multiple datasets on the wire that way.

regards, tom lane